The Physics of Solids - Physics for Game Programmers - page 350

Table 12-1. NIJ Body Armor Classification Standards

Classification Max Kinetic Energy ( J )

Type I 302

Type IIA 569

Type II 930

Type IIIA 1483

Type III 3371

Type IV 4078

The NIJ body armor tests were conducted by shooting bullets at body armor at a distance
of about 3 m . The types of bullets tested and their mass and reference velocities are shown in
Table 12-2. The abbreviation FMJ stands for “full metal jacket” and indicates a bullet consisting
of a lead core covered with a copper-zinc alloy jacket. The abbreviation RN indicates a bullet
with a round nose. A jacketed soft point (JSP) bullet, also known as a semijacketed bullet, consists
of a lead core surrounded except at the tip with a metal covering. A jacketed hollow point (JHP)
bullet is similar to a JSP bullet except a hollow cavity or hole exists at the nose. The last two
bullets in the table, the ones with the highest kinetic energy values, are military bullets.
The velocities listed in Table 12-2 were measured 2 m away from the muzzle of the gun
barrel. At that distance, it is a reasonable approximation to assume the measured velocity was
equal to the muzzle velocity of the bullet. The measured velocities had an approximate error of
plus or minus 9 m/s and are representative values for the particular bullet type. Different brands
of the same type of bullet might have higher or lower velocities than the values shown in
Table 12-2. Three different types of 9 mm bullets were tested, having approximately the same
mass but different reference velocities.

Table 12-2. Specifications of the Bullets Used in the NIJ Body Armor Tests

Bullet Mass ( kg ) Reference

Velocity ( m/s )

Kinetic Energy ( J )

.22 caliber Long Rifle RN 0.0026 329 141

.38 ACP FMJ RN 0.0062 322 321

9 mm FMJ RN 0.008 341 465

9 mm FMJ RN 0.008 367 539

0.40 S&W FMJ 0.0117 322 607

9 mm FMJ RN high velocity 0.0082 436 779

.357 Magnum JSP 0.0102 436 969

.44 Magnum JHP 0.0156 436 1483

7.62 mm NATO FMJ 0.0096 838 3371

.30 caliber M2 armor piercing 0.0108 869 4078